As used herein, the term "semiconductor component" refers to an electronic component that includes a semiconductor die, or that makes electrical connections to a semiconductor die. Exemplary semiconductor components include semiconductor packages, multi chip modules, wafers, interconnects, and test carriers for testing dice and packages.
Conventional semiconductor components include external contacts that allow electrical connections to be made from the outside to the integrated circuits contained in the component. For example, semiconductor packages can include external contacts such as solder balls, formed in a ball grid array (BGA) on a substrate of the component.
Besides the external contacts, semiconductor components can also include internal contacts formed on different surfaces of the substrates than the external contacts. For example, semiconductor packages can include bond pads for wire bonding to the dice contained in the packages. Typically, the bond pads are located on a first surface of the package, and the external contacts are located on a second surface of the package. As another example, test carriers for testing semiconductor components, such as bare dice, and chip scale packages, include internal contacts for making temporary electrical connections to the external contacts on components being tested. In addition, the test carriers include external contacts such as pins or balls for making electrical connections to a test board and test circuitry.
With each component electrical paths must be provided through the component, for electrically interconnecting the external contacts to the internal contacts. One method for providing the electrical paths is by forming vias between the contacts, and then filling the vias with a conductive material. For component substrates formed of an etchable material, such as silicon or ceramic, the vias are typically etched in the substrate using a wet or dry etchant. For substrates formed of plastic, such as a glass filled resin (e.g., FR-4), the vias are typically molded, or machined in the substrate.
One problem with interconnecting contacts on semiconductor components is that with advances in semiconductor manufacture, the size and spacing of the contacts is decreasing, and the total number of contacts on a single component is increasing. A chip scale package, for example, can include a hundred, or more, external contacts each having a diameter of only about 10 mils, and a pitch of only about 30 mils.
Interconnecting small, densely spaced, contacts on semiconductor components requires small, densely spaced conductive vias. Because of their small size it can be difficult to fill the vias with a conductive material. Also because of the required size and spacing of the contacts, complex electrical paths must sometimes be provided through the component. Signal delays and high resistivity can result from complex electrical paths.
Furthermore, the conductive vias must sometimes be electrically connected to the contacts using a bonding technique, such as soldering, or wire bonding. The small size of the contacts and vias makes the bonding process difficult. For example, bonding solder balls to metal filled vias can be made difficult by the small size of the solder balls and vias. In a similar manner wire bonding to metal filled vias can be difficult.
The present invention is directed to an improved method for fabricating semiconductor components with small, closely spaced contacts.